[scotsman60]

OK,

I mixed 5 gallons of 100 octane ($4.50/gallon) with 13 gallons of 91 when I filled up last night.

The pinging is almost completely gone and the motor appears to run cooler!!!

I'm feeling better, but not completely satisfied for two reasons:-

1) I got stuck in stop and go traffic going through Laguna Beach and the motor temp went up. The needle went to just above horizontal - about two thirds of the way between the first and second tick. At this temp the engine pinged under acceleration from low revs. I can live with this fairly easily because it's easy to avoid - keep my foot off the gas (OK - not so easy....)

2) 100 octane gas is not that easy to find and it's expensive.

I'm going to research octane boosters - this may be more economical and easier to live with than trying to find 100 octane all the time. I'm not convinced that mixing is an issue - if I put the booster into an empty tank and then top up with a full tank of gas I reckon that the mixing will be pretty good. If they all make a mess insude the engine then that would be a concern.....

Any suggestions for keeping the temps down in stop and go traffic? I have the under-tray removed already. Can I use a different thermostat (or adjust the existing one) so that the oil cooler kicks in earlier? Will this have a significant effect on the cylinder head temps?